When an electromagnetic wave is propagated in a substance with a high dielectric constant, the wavelength thereof will get shorter. With such characteristics, the conventional metal material may be substituted with a dielectric material to reduce the volume of the filter under the same requirements. The research on the dielectric filter is always a hot point in the communication industry. The filter acts as an important component in the wireless communication product. The dielectric filter, especially the dielectric resonator constituting the dielectric filter, is of particularly important meaning for miniaturization of the communication product.
In general, a single-ended conductive dielectric resonator, as shown in FIG. 1, is primarily comprised of a dielectric resonant column 103, a sealing cover plate 102, a tuning screw 101, and a metal cavity 104.
According to the working principle of a Transverse Magnetic (TM) mode dielectric resonant cavity, when the single-ended conductive dielectric resonator operates normally, an upper end face of the dielectric resonant column 103 does not contact with a lower end face of the sealing cover plate 102, and there is a high electric field distribution in a portion where the lower end face of the dielectric resonant column 103 contacts with the metal cavity 104. If the lower end face of the dielectric resonant column 103 contacts with the metal cavity 104 insufficiently, it will result in that a resistance is discontinuous, the energy of the field cannot be transmitted, and a high dielectric constant and high quality factor of the medium cannot be achieved, or even that the medium will be burned out. Therefore, whether the lower end face of the dielectric resonant column contacts well with the end face of the metal cavity in the single-ended conductive dielectric resonator is especially crucial. How to solve the fixing and contact between the lower end face of the dielectric resonant column and the end face of the metal cavity in the single-ended conductive dielectric resonator becomes an important research direction in the application of the dielectric filter.
The existing single-ended conductive dielectric resonator is shown in FIG. 1, in which the lower end face of the dielectric resonant column 103 is welded directly on the metal cavity 104, to closely contact with the bottom face of the metal cavity 104. The sealing cover plate 102 is sealed together with the metal cavity 104 using a screw, to form a closed cavity. As the dielectric resonant column 103 is welded directly on the bottom of the metal cavity 104, there are very high requirements on the welding process, and there may be a shedding phenomenon in the whole process of welding the dielectric resonant column 103, which may seriously influence the performance and working life of the filter.
In the Chinese patent CN201020138885, there is provided a dielectric resonator including a dielectric resonant column, a cavity, and a cover plate, wherein the dielectric resonant column is arranged in the cavity, further comprising: a metal base of the dielectric resonant column, wherein a bottom face of the dielectric resonant column is welded at a first end of the metal base, the metal base is fixed on the bottom face of the cavity through a screw, and there are sharp teeth around a contact face between a second end of the metal base and the cavity, to reduce a contact area between the metal base and the bottom face of the cavity. In a specific implementation process of this patent, the assembly process is complex, and there are high requirements on the structural design and high influence on the performance, which are disadvantageous for mass production and cause high cost.